Method of making motor-compressor unit for refrigeration



A. A. KUCHER 2,243,464

METHOD OF MAKING MOTOR-COMPRESSOR UNIT FOR REFRIGERATION May 27, 1941 Original Fiied Sept. so, 1932 '4 Sheets-Sheet 1 3 1 n. I. 7 I

AT'rolgwEys.

METHOD OF MAKING MOTOR-COMPRESSOR UNIT FOR REFRIGERATION Original Filed Sept. 30, 19:52 4 Sheets-Sheet 2 ATTORNEYS,

A. A. KUCHER v 2,243,464 METHOD OF MAKING MOTOR-COMPRESSOR UNIT FOR REFRIGERATION 4 sheets-sheet 3 Original Filed Sepi. 30, 1932 INVENTOR. M W M ATTORNEYS.

May 27, 1941. A. A. KUCHER METHOD OF MAKING MOTOR-COMPRESSOR UNI'I FOR REFRIGERATION Original Filed Sept. 30, 1932 4 Sheets-Sheet 4 BY W ATTORNEYS.

Patented M4, 21, 1941 METHOD or name uo'ron-comnnsson mvrrron nsrmoaaumn Andrew A. Kucher,

Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a

corporation of Delaware Original application Sep tembcr 30, 1932, Serial Divided and this 3., 1937, Serial No. 139,989

application April 9 Claims. (Cl. 29156-4) This invention relates to refrigeration and more particularly to the manufacture of a motor-compressor unit for use in refrigerating sys- This application is a division of my copending application Serial No.-635,556, filed September 30, 1932, which became Patent No. 2,130,349, patented Sept. 20, 1938.

It is among the objects of this invention to provide a motor-compressor unit which may be made very accurately, and is capable of operating at very high efllciencies notwithstanding the fact that the parts are easily made for quantity production and may be assembled without troublesome selectivity.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings: I

Fig. l is a view, partly in vertical cross-section and partly diagrammatic of a refrigerating system including the motor-compressor unit;

Fig. 2 is a horizontal cross-sectional view taken along the line 272 of Fig. 1;

Fig. 3 is a vertical cross-sectional view taken along the line 33 of Fig. 1;

Fig. 4 is a bottom view of the unit shown in Fi 1;

Fig. 5 is an exploded" view of the unit, particularly useful in showing the various steps of assembly of the unit;

Figs. 6 to 13 inclusive illustrate the various steps which may be performed by standard machine tools in the manufacture-of the compressor unit;

Fig. 14 is a cross-sectional view of a portion of the mechanism shown in Fig. 2 with a slightly modified form of divider;

Fig. 15 is a cross-sectional view somewhat similar to Fig. 1, but with the drive shaft shown in elevation;

Fig. 16' is a cross-sectional view taken along the line lG-IS of Fig. 1. This figure indicates by the line [-4 the cross-section along which Fig. 1 is taken; and

Fig. 17 is a cross-sectional view looking down on the top of the compressor.

According to this invention it is possible to produce a motor-compressor unit in which sub stantially all of the parts can be accurately and cheaply made and which-the assembly may be performed speedily and without the necessity of careful lapping or Notwithstanding this case of manufacture, a unit made in accordance with this invention is of extremely high efllciency and is capable of operating at,

exceptionally low current consumption and high refrigerating efficiency.

While this unit is particularly adapted to manufacture by the use of the simplest of machineshop tooling operations, it is to be understood that many of the features and advantages of this invention may be utilized where a more specialized tool equipment is desired either by preference or because of prior acquisition.

In the manufacture of this motor-compressor unit, advantage is taken of the extreme accuracy of certain types of standard or special tools, when they are limited to producing cylindrical surfaces about a common axis or of a predetermined eccentricity and also when they are limited to producing plane surfaces at right angles to the axes of the cylindrical surfaces. The moving parts of the unit, which must maintain close tolerances in order to operate freely and to maintain fluid seals during the compressing operation, may be finished by standard grinding tools which produce accurately cylindrical surfaces about any desired axis and plane surfaces at right angles to such axis.

The motor-compressor unit is manufactured preferably by forming a cup member with certain parts of'the unit assembled therein and by forming a sealing member with other parts of the unit assembled thereon and thereafter assembling these two members by telescoping cylindrical surfaces with each other and by abutting plane surfaces with each other. The entire assembly is guided by a stationary shaft which 'is rigid with respect to one of the members and slides into aslot or cylindrical receiving surface in the other member, the working parts of the unit thus being brought together easily with the least likelihood of distortion or binding and with extreme accuracy. I

The cup member, above referred to, preferably has the motor stator assembled therein. The sealing member has the motor rotor, the working parts of the compressor assembled thereon,

and the rigid stationary shaft secured thereto for guiding the final assembling operation.

In the particular embodimentdisclosed, the

cup member is shown at ill, with the motor stator Ii therein. The sealing member is. shown at i2 and carries a stationary shaft II, a motor rotor i4 and a compressor shown below the rotor I i, the compressor including a stationarypumping cylinder II and arotary piston It. The

motor and the compressor are drivingly con-.

' angle tothe said common axis.

nected by means of a drive shaft, sleeve or eccentric l1,- these parts being all produced with cylindrical cooperating surfaces in a manner more fully to be described.

Some of the preferred steps in the production of the cup member are shown at Fig. 6. The shell of the member II is first roughly produced by a drawing operation from deep drawing steel. This operation is well-known and need not be specifically illustrated. This drawing operation produces the general outline of the shell ll, with a substantial thickness of material throughout the shell. The .shell thus roughly formed is placed in a fixture 20 held on the rotating spindle 2! of a standard grinding machine, and several' cylindrical surfaces, preferably internal, are

- produced therein by an internal grinding machine or a lathe,whose rotary grinding member of cutting tool is diagrammatically shown at 22, and by a reaming device 23. One or more plane surfaces also are produced by face grinding, while the cup member II is held in the fixture. to insure that all cylindrical surfaces are truly coaxial to. the common axis of the member Ill and that the plane surfaces are at a true right Thus the internal cylindrical surface 24 is produced for the reception of the stator II. The internal cylindrical surface 25 is producedf'so that the stator may be inserted in the member Ill without undue resistance. An internal cylindrical surface 26 is produced for the reception of the sealing member l2 in a manner hereafter to be more fully described. Also an internal cylindrical shaft receiving surface 21 is produced, preferably by the reaming device 23. These surfaces.

24 to 2| inclusive are truly coaxial because cup member HI is maintained in the fixture 20 and rotates with the spindle 2|. In addition, one or pin 36 on the machine-tool member 34 which cooperates with the recess 31 to be more fully.

' hereafter described. By cylindrical grinding drical grinding members about a common axis without disturbing the set-up. In addition, the plane abutting surface 4| and the-plane compressor receiving surface 44 are produced'by face grinding operations-indicated at 45 and 46. Since these are also produced on the same setup, they are truly at right angles to thecommon Y axis of the sealing member.

The drive shaft I1 is also finished by grinding operations diagrammatically shown in Fig. 8. The rough blank of the drive shaft is formed with an internal cylindrical bearing surface 41 preferably by a reaming operation (not shown) and thereafter is mounted on a mandrel 4| which cooperates with the internal cylindrical bearing surface. The drive shaft fits snugly on the mandrel. The motor' rotor receiving surface 49 is roughly straight knurled in any suitable manner, or may be made tapered in order more plane are produced on the member l|. Thus the plane surface 2| is produced as a stop for thestator Ii, the plane abutting surface 2| is produced for receiving the corresponding abuttingsurface on the sealing member l2 hereafter' to be described. The surface ll need not be atrue plane surface, but conven iently can remain as formed by the internal 4 grinding tubes.

The motor stator II is forced into the cylindrical surface 24 'of the member' II by any standard press. The stator ll preferably is formed with an external cylindrical surface 3| and an internal cylindrical surface 32, these surfaces being rendered substantially coaxial during the manufacture of the stator so that when a stator is forced into the surface 29, the internal cylindrical surface 32 of the stator wfll be substantialy coaxial with the common axis of the member l| within tolerances required for propercooperation with the motor rotor.

The sealing member I! preferably is made of deep drawing steel and is stamped roughly to the shape shownin Fig. 7. This member .has welded thereto a stamped plate. 3| and a stationary shaft ii, the plate 3| and the shaft I| being welded so thatthey are substantially integral with the sealing member 12. The plate 33 has an annular groove "a adjacent the shaft l3 for the reception of a thrust washer 33b hereafter to be more fully described. After the welding operation, .the sealing member is cengrindingmachine and fixed to be rotated by to effect a driving fit between the motor rotor I4 and the surface 4|. The .surface 49 need not be finished to relatively close limits since ultimately it is necessary only to maintain the rotor-stator gap. The mandrel 4| is eccentrically mounted on the centers 5| and II and is driven by the dog 52 and by the chuck at II. External eccentric cylindrical surfaces 53 and 54 are ground on the drive shaft by means of external cylindrical grinding member 55. The motor rotor II is produced with an internal cy lindrical surface N and an external cylindrical surface 51, so that the same may .be forced on 1 tered on the members 34 and 3! of a cylindrical the drive shaft by any standard press operation and so that the external cylindrical surface I! is substantially coaxial with the internal cylindrical surface 4] within the tolerance required for proper cooperation with the motor stator ll. However, if the surface 4| has been made tapered or conical, the internal surface 5| of the rotor is also made conical to cooperate therewith. It is to be understood, however, that the motor stator l4 may be assembled on the drive shaft and its external surface I! may be ground by placing the mandrel on the center position in a lathe, so that the surface 51 may be made truly coaxial with the internal surface 41.

The compressor is preferably formedof a stationary pumping cylinder II and a rotary piston I|. The pumping cylinder ll preferably is formed as shown in'Figs. 9 to 12 inclusive. The rough blank, which may be a roughly formed annulus, has a slot formed therein and finished to accurate dimension by the face grinding tool 8! while held in the vise or fixture |2. Preferably the slot II is formed parallel with the radius of the annulus. The notches |I are also cut adjacent the slot Thereafter a motor spacing block N, which has been made very chuck G1 which is held on the rotary spindle 83. While in this position, an internal cylindrical surface 63 is formed by an internal rotary grinding tool II, and one end plane surface II is face out by the radial grinding tool 12. Since these two surfaces are ground while the annulus is in the chuck 81, the surfaces 88 and H are truly. at right angles to each other. The annulus is then placed on a magnetic chuck I3 and the other end plane surface 14 is produced by the surface grinding tool 18. This is a standard grinding machine which insures a truly parallel relationship between the surfaces H and "I4 and therefore insures that the surface 14 is also at right angles with surface 69. The clamp 68 and the block 83 remain on the annulus for permits the grinding tools to finish the surfaces closely on the bearing surface of the shaft a further assembling step hereafter to be more rough annulus is placed in a chuck similar to thechucktl, but of smaller size to accommodate the piston l8 and an internal cylindrical surface 16 is out by an internal grinding operation similar to that produced by the tool 10 on the surface 68. Also one end plane surface TI is cut by a face grinding tool similar to the tool 72, producing the surface l1 truly at right angles, internal cylindrical surface 18. Thereafter the annulusis assembled tightly on the mandrel 18 and an external cylindrical surface 19 is ground by placing the mandrel 78 on the center members 8d and 8! and by producing a cylindrical grinding action by the tool 82. This operation insures that the surfaces 18 and i9 are truly coaxial. Thereafter the annulus i8 is placed on the magnetic chuck similar to the chuck it with the surface Tl adjacent the chuck and the end plane surface 83 is ground by a surface grinding tool similar to the tool 15 to insure that the plane surfaces ii and 83 are truly parallel with each other and at right angles to the axis of the piston it.

Proper bolt holes, threaded and plain, are produced on the parts wherever necessary. The

bolts need not have a tight fit on the plain holes,

because the parts are held in place by the longitudinal clamping action of the bolts.

The foregoing operations described with respect to Figs. 6 to 13 inclusive, may be produced on standard tools, utilizing carefully made mandrels or blanks, and as will be understood by one skilled in the art, such procedure may be made to insure coaxiality and perpendicularity within any reasonable tolerance desired, so that the parts so produced will have cylindrical surfaces coaxial with each other, or eccentric with .each other to any degree of eccentricity desired and with plane surfaces at right angles to the cylindrical surfaces within any degree of perpendlcularity desired. While these parts may he made on standard machine-shop tools, it is. to be understood that special tools may be used to produce the parts, if so desired.

A thrust bearing is provided to support the weight of the drive shaft l1 and the rotor M.

This may be provided by forming an annular channel in the plate 33 adjacent the shaft l3 for the reception of a hard 'seel split ring 33b 1 which extends slightly above the surface of the plate 33. Preferably the shaft I 3 has a cavity I28 of smaller diameter than its bearing surface adjacent the groove for the ring 33b. This extend through the sealing member If.

and is of such a size that it is a proper guide for the stationary pumping cylinder IS. The

pumping cylinder l5 withthe 'block 83 and clamp 64 still in place is telescoped over the mandrel 85 and is securely fastened to the plate 33 by means of the bolts 86. These bolts are of sumcient power, so that when the clamp 64 is released, they firmly hold thestationary cylinder IS with exactly the same spacing in the slot 88 which prevailedwhen the clamp was in place. Thereafter the mandrel 85.is manually removed by means of the knurled surface 81 which extends above cylinder li when the cylinder is in place. The rotary piston I6 is placed within the stationary cylinder 85 and the top cover plate 88 of the compressor is clamped to the cylinder l5 by means of screws 88. The .top plate 88 is formed with the bottomsurface 90 as a true plane surface and the cylinder 85 and piston l6 are made substantially of the same length but with the .cylinder l5 just slightly longer (about .0004 inch extra length in a small household model), so that when the plate dll isin place; the end surfaces 17 and 83 will have a sealing relation with respect to the surfaces 88 and se because of the oil film produced as hereinafter more fully described. After the plate 85 is in place, the oil cup member 8! is secured by means of screws 92 to the plate 86 with the gasket 910. between. The split thrust washer 38b which has a radially disposed oil passage the shaft ll. Thereafter the cup member l8 and the sealing member 12 are assembled by a telescoping the cylindrical surfaces 28 and 38,

by abutting the plane surfaces 28 and 43 and by telescoping the end 93 of the shaft l3 in the cylindrical surface Zlof the member l8. When these members have been driven in place, the end 90 of the cup member is curled around theflange 88 of the sealing member l2 and is soldered or brazed as shown at 38.

Other features may be embodied in the motorcompressor unit to enhance its emciency without impairing the ease of manufacture. Thus the stationary shaft 83 may be made hollow and may This 1 hollow shaft may have a radial opening I08 to receive the compressed refrigerant which then flows through the longitudinal passage Iii of the shaft l3 and'is discharged into the pipe ll! connected to the end of the shaft 13. From thence the refrigerant flows to the condenser I33, and,

in a liquefied form, flows through the pipe I to the heat interchanger ill! and from thence 4 V to the expander Ill, then through the evaporator [l1 and through the interchanger I. and pipe Ill to the inlet fixture 31. The inlet fixture 31 may be in the form of a nipple which passes through the sealing member I2 and is held in place by the plate 33 when it is welded. The

nipple may also include a screen III, the plate the space between the cylinder I5 and the rotary piston IS.

The cylinder I5 is provided with a divider or follower 66 of substantially the same length as the piston I. This divider is provided with one or more cylindrical pins II I around which are placed springs II2 which bear radially outwardly against the inverted oil cup portion II3 of the oil cup member SI. If desired, the divider is provided with a half moon member III to increase the sealing surface adjacent to the rotary piston It as shown in Fig. 2, or the end may be made fiat, being tangential to the piston, as shown in Fig. 14.

Oil is placed in the unit to the level III, and, since the oil is under compression pressure, and leaks slowly along thefollower I, the oil will be forced up into the inverted cup-shaped member H3 and thus lubricate the entire vertical extent of the spacer or follower I.

Lubrication for the internal portion of the compressor and for the bearing'or bearingson the stationary shaft I3 are provided. For this.

purpose the oil cup member 3| is provided with an upper oil cup I20, A gasket am is interposed between the member I20 and the plate 3., so that the space inside of the cup I2! is substantially oil tight. a discharge opening I22 and with a valve I23 which seats on the annular valve seat I24. The compressed refrigerant, together with the oil which is forced past the divider I8 is discharged up through the passageway I22 and past the "valve I23, comprising a metal reed secured by the screws I23a. to the plate 38, into the cup compartment I23. This tends to fill the compartment with a substantial quantity of oil which thus submerges the opening I25 in the plate 3| in oil. A certain part of the oil from the compartment I23 forms a secondary lubricating cycle by fiowing radially outwardbetween the piston I! and the plates 38 and 33 to be again discharged through the discharge opening. I22 into the compartment I23. Another part of the oil from compartment I2. is forced upwardly between the stationary shaft I3 and the drive shaft I! to lubricate their cooperating bearing surfaces. To

this end, the oil flows down between the eccentric surfaces 53 and I4 and the internal cylindrical surface I. of the piston I6, providing proper lubrication at this point, and is given a forcefeed action by the groove I2! cut in the eccentric surfaces 53 and N. This forces the oil down to between the stationary shaft and the drive'shaft.

some of the oil passing through this latter beara being provided with a passage m leading to ing is discharged radially along the rotor and fiows back to the oil space in the bottom of the compressor unit. The refrigerant discharged into the cup member I fiows through the annular opening I32 and thence through openings I33 in the rotor ll to the space above the rotor, so that the gas andoil are given separating action while flowing through the openings I33. The gas to the openings Ill and the oil flows radially outward and back through the rotor stator space by gravity to the bottom of the compressor unit. Suitable electrical lead-ins I34 are provided in the sealing member I2, for connecting the stator with the source of power. A suitable plug I3! is provided for filling or draining the unit.

The plate "is provided with a unit, These fins may be formed of a single piece of metal bent in a zig-zag manner as shown in The outer surfaces of the shaft and the upper surface of the plate I ll may be given a hard finish preferably by a chrome plate finish. This finish may be applied electrochemically. To this end the grinding operations on the steel may be carried'out by giving allowance for subsequent plat ing, after which careful chrome plating may be performed with subsequent burnishing of the finish.

The motor rotor may be provided with counterbalances Ill and Ill The combined moments of the counter-balance III and of the rotary parts of the compressor are made'equal to the moment of the counter-balance I13, thus providing a dynamic balance in the unit.

The length of the surface 26 and of the flange 38 are such that the curled portion "2 may be ground of! and the unit disassembled three or more times. when the unit is reassembled, the length of the fiange 3l-is reduced sufficiently to permit another portion of the surface 2' to be curled around the end.

Preferably adjacent parts of the unit which bear against each other are made of different hardness. Thus the plate 33 and the shaft I3 are made of soft steel with their bearing surfaces chromium plated as described above. The rotary piston I. is made of soft steel and is glass hardened. The shaft I I is soft steel, hardened slightly less than the piston II, but the outside surface may alternately be chromium plated. The cylinder II is soft steel, heat treated by alternate heating and cooling, to relieve internal strmses; The follower 88 is made of soft steel, glass hardened slightly less than piston IO. The cover plate is made of soft steel, heat treated similarly to cylinder I 5. The cup member I 3 and the sealing member I2 are made of stamp stock, preferably of soft drawing steel.

This motor-compressor unit is particularly adapted for use in refrigerating where the compressor unit operates continuously as described in my copending application Serial No. 599,239. It is also particularly adapted for use with a refrigerant and lubricant which are completely miscible in each other whether the compressor operates continuously or not. It also may be used for intermittent operation or with refrigerants and lubricants which are not completely miscible in each other.

This motor-compressor unit is particularly adapted to be made without the use of cast metal.

While the form of embodiment of the invention as herein disclosed, constitutes apreferred form,

it is to be understood that other forms mightbe adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. The method of manufacturing a compressor part which comprises producing a cup-shaped member by a drawing operation, securing said member to a face plate of a lathe, and while thus secured removing material from the inside of said cup-shaped member so as to form a plurality of cylindrical surfaces all coaxial about the common axis of said member and to form a plane abutting surface on said member at right angles to said common axis.

2. The method of manufacturing a motorcompressor unit which comprises producing a cup-shaped member by a drawing operation, re-

' ishing to size the internal cylindrical surface and moving material from within said cup-shaped member so as to form coaxial surfaces on the cup member with a plane surface perpendicular to said surfaces, forming a sealing .end member with coaxial cylindrical surfaces and with a plane drical surfaces, securing annular portions of a motor and a compressorto said members coaxially to said cylindrical surfaces respectively, and telescoping said members in sealing engagement with two cylindrical surfaces on one member nesting in two cylindrical surfaces of the other memher, and with said plane surface abutting each other.

.3. The method of manufacturing acompressor I cylinder with a divider block slot which comprises forming a slot in a-roughly formed annulus and finishing the slot to size, clamping a spacing block in the slot and finishing to size the internal cylindrical surface of the annulus, and machining the end surfaces parallel to one another and perpendicular to the internal cylindrical surface.

4. In the manufacture of a rotary compressor, the method comprising forming a compressor cylinder member with a divider block slot by cutting a slot in a roughly formed annulus and finishing the slot to size, clamping a spacing block in the slot, finishing to size the internal cylindrical surface and the end surfaces of the annulus, securing the cylinder to a rigid end wall and thereafter to size, clamping a spacing block in the slot, finsurface perpendicular to said last named cylinsaid block. I

8. The'method of manufacturing a compressor shaft with an external eccentric cylindrical surthe end surfaces of the annulus, plating an end wall member with a chrome-like material,securing the annulus to the end wall member, removing the spacing block, forming a rotary piston, forming a'drive shaft with an external eccentric cylindrical surface, forming a second end wall member, mounting the piston and the eccentric portion of the shaft within the annulus, securing v the second end wall member in place.

7. The method of manufacturing a compressor cylinder with a divider block slot which comprises forming a-slot in a roughly formed annulus and finishing the slot to size, clamping a spacing block in the slot and finishing to size theinternal cylindrical surface of the annulus, securing an end wall to said annulus, and thereafter removing cylinder with a divider block slot which comprises forming a slot in a roughly formed annulus and finishing the slot to size, clamping a spacing block in the slot and finishing to size the internal cylindrical surface of the annulus, machining the end surfaces parallel to one another and perpendicular to the internal cylindrical surface, se-

curing one end wall to said annulus while said block is clamped in place and securing the other end wall to said annulus after removal.

9. In the manufacture of a, rotary compressor the method comprising cutting a divider block slot in roughly formed annulus, finishing the slot to size, clamping a spacing block in' the slot, flnishing to size the internal cylindrical surface and the end surfaces of the annulus, plating an end wall member with a chrome-like material, securing the annulus and the end wall member together, forming a rotary piston, forming a drive face, mounting the piston and the eccentric portion of the shaft within the annulus, and securingthe second end wall member in place.

ANDREW A. KUCHER.

inserting a divider 

